This invention relates to an apparatus having a film condition judging device in which bar codes of the film cartridge are read out by a sensor, and the used condition of a film is judged based on output from the sensor.
Conventionally, in an apparatus such as a camera which uses a film cartridge (a film is contained therein) having a bar code disk in which data on a film is recorded, it has been known that, after loading the film cartridge in the camera, bar codes of the bar code disk are read out by sensors equipped in the camera, and the film's used condition (exposed, unexposed, etc.) is judged by output from the sensors, and then operations in the camera are controlled depending on the film's used condition. In order to judge the film condition, two sensors which monitor a different position of the bar code disk, have been generally used.
In the above-mentioned conventional method, however, it is true that the film condition can be correctly judged, but on the other hand, two sensors are needed, which requires two sensor driving circuits and two sensor's output detecting circuits, so its costs are to be raised.
Theoretically, it seems possible to practice a method of judging the film condition by one sensor. However, if the above-mentioned method is applied, after a motor for feeding the film is ON, friction between a driving shaft linked with a motor and a spool shaft of the film cartridge may make a rotation of the bar code disk unstable before they engage with each other to rotate the bar code disk. Thereby the sensor may erroneously read out the bar codes, and so give an error signal. Thus, in the method of judging the film condition by one sensor, it is difficult to correctly judge the film condition.